1. Field of the Invention
This invention relates to heaters and more particularly to a portable oil field heater with the walls both water cooled and air cooled.
2. Description of the Prior Art
Before this invention, heaters were mounted upon skids for transportation or upon the beds of trucks, and were used in the oil field to heat mixtures of petroleum and water. Also, heaters were used to heat oil alone. Normally, the walls of the heater were insulated by fire block, which rapidly deteriorated due to the rough roads and rough handling to which the heaters were subjected.
Before this application was filed, a search was made in the U.S. Patent and Trademark Office. That search developed the following U.S. patents:
Stewart: U.S. Pat. No. 1,980,301 PA1 Thomas: U.S. Pat. No. 2,079,191 PA1 Hassler et al: U.S. Pat. No. 2,081,927 PA1 Schlenz: U.S. Pat. No. 2,586,998 PA1 Olson et al: U.S. Pat. No. 2,699,155 PA1 Richardson: U.S. Pat. No. 3,119,438 PA1 Coggins et al: U.S. Pat. No. 4,289,093 PA1 Ruhe et al: U.S. Pat. No. 4,290,388
These patents are considered pertinent because the applicant believes the Examiner would consider anything returned by the searcher to be relevant and pertinent to the examination of this application.
It is noted that Stewart discloses an oil heater mounted upon a truck.